Added missing descriptions US1657389. (#19710)

* Added missing descriptions.

* Edited description.

Author: jdmartinez36

docs/csharp/programming-guide/xmldoc/include.md

@@ -1,5 +1,6 @@
 ---
 title: "<include> - C# programming guide"
+description: Learn about the XML <include> tag. This tag lets you refer to comments in another file that describe the types and members in your source code.
 ms.date: 07/20/2015
 f1_keywords:
   - "include"

docs/csharp/programming-guide/xmldoc/list.md

@@ -1,5 +1,6 @@
 ---
 title: "<list> - C# programming guide"
+description: Learn about the XML <list> tag. This tag is used to create tables and definition, bulleted, or numbered lists by using 'item' blocks.
 ms.date: 07/20/2015
 f1_keywords:
   - "list"

docs/csharp/programming-guide/xmldoc/para.md

@@ -1,5 +1,6 @@
 ---
 title: "<para> - C# programming guide"
+description: Learn about the XML <para> tag. This tag lets you add structure to the text in another tag, such as <summary>, <remarks>, or <returns>.
 ms.date: 07/20/2015
 f1_keywords:
   - "<para>"

docs/csharp/programming-guide/xmldoc/param.md

@@ -1,5 +1,6 @@
 ---
 title: "<param> - C# programming guide"
+description: Learn about the XML <param> tag. This tag is used in the comment for a method declaration to describe one of the parameters for the method.
 ms.date: 07/20/2015
 f1_keywords:
   - "param"

docs/csharp/programming-guide/xmldoc/paramref.md

@@ -1,5 +1,6 @@
 ---
 title: "<paramref> - C# programming guide"
+description: Learn about the XML <paramref> tag. This tag gives you a way to indicate that a word in the code is a parameter.
 ms.date: 07/20/2015
 f1_keywords:
   - "paramref"

docs/csharp/programming-guide/xmldoc/permission.md

@@ -1,5 +1,6 @@
 ---
 title: "<permission> - C# programming guide"
+description: Learn about the XML <permission> tag. This tag lets you document the access of a member, while the PermissionSet class lets you specify access to a member.
 ms.date: 07/20/2015
 f1_keywords:
   - "permission"

docs/csharp/programming-guide/xmldoc/processing-the-xml-file.md

@@ -1,5 +1,6 @@
 ---
 title: "Processing the XML file - C# programming guide"
+description: Learn about processing the XML file in C# programming. See code examples and view additional available resources.
 ms.date: 07/20/2015
 helpviewer_keywords:
   - "XML processing [C#]"

docs/csharp/programming-guide/xmldoc/recommended-tags-for-documentation-comments.md

@@ -1,5 +1,6 @@
 ---
 title: "Recommended tags for documentation comments - C# programming guide"
+description: Learn about the recommended tags for documentation comments. See a list of recommended tags and view additional available resources.
 ms.date: 01/21/2020
 helpviewer_keywords:
   - "XML [C#], tags"

docs/csharp/programming-guide/xmldoc/remarks.md

@@ -1,5 +1,6 @@
 ---
 title: "<remarks> - C# programming guide"
+description: Learn about the XML <remarks> tag. This tag is used to add information about a type, supplementing the information specified with <summary>.
 ms.date: 07/20/2015
 f1_keywords:
   - "remarks"

docs/csharp/programming-guide/xmldoc/returns.md

@@ -1,5 +1,6 @@
 ---
 title: "<returns> - C# programming guide"
+description: Learn about the XML <returns> tag. This tag is used in the comment for a method declaration to describe the return value.
 ms.date: 07/20/2015
 f1_keywords:
   - "returns"